1. Technical Field
The present invention relates to an electrochemical cell and a method of manufacturing an electrochemical cell.
2. Related Art
In the past, an electrochemical cell such as an electric double layer capacitor or a nonaqueous electrolyte battery was used as a backup power source of a clock function, a backup power source of a memory or a semiconductor, a standby power source of an electronic device such as an IC memory or a microcomputer, a power source of a solar clock or a driving motor, and the like. In recent years, the electrochemical cell has been examined as a power source of an electric automobile, an auxiliary electric storage unit of an energy conversion/storage system, or the like.
Particularly, since a surface-mountable electric double layer capacitor can be decreased in size or height, the electric double layer capacitor is suitable for a slim portable device. The electric double layer capacitor includes a container in which an opening of a concave portion is sealed and an external electrode which is formed on an outer surface of the container. The container accommodates an electrode active material used as a positive electrode and a negative electrode, a current collector connected to the electrode active material, and an electrolytic solution. In addition, the external electrode and the current collector inside the container are electrically connected to each other.
As the container of the electric double layer capacitor, a resinous container has been examined. However, in general, since a resin has a low gas barrier property and high moisture permeability compared with metal, moisture enters into an electrode portion, and the electrolytic solution and the moisture react with each other at the time of the application of the voltage, which may cause deterioration such as a decrease in storage amount of the capacitor. In addition, in the case where a lead frame is adopted together with the resinous container so as to connect the current collector inside the container to the external electrode, since the adhesiveness between the resin and the lead frame is poor, a leakage of a liquid may occur.
In addition, as the container of the electric double layer capacitor, a ceramics container has been examined. In the ceramics container, in the case where the current collector inside the container is connected to the external electrode by using a metal layer (refer to JP-A-2001-216952), since it is necessary to use a metal layer capable of enduring a sintering temperature of the ceramics, the manufacturing cost increases. In addition, in the ceramics container or the glass container, in the case where the current collector inside the container is connected to the external electrode by using a via (for example, refer to JP-A-2000-294454), it is necessary to use a high-cost material and to perform a complex process such as plating on the via or polishing on the embedded electrode. Further, a leakage of a liquid may occur through the via.